The Intake Manifold: Clean and Shine

Intake manifold still in the car (Volvo P1800E 1970).

Below are photos before removal of the attachments and cleaning (Click for full size photos).

Intake before the bulk of the repolishing, but after loosing polish in the wheel cleaner mishap ( see text below).

A manifold of issues cleaning the manifold. After stripping the intake of all the hose fittings, throttle plate, TPS, and cold start injector, the first cleaning attempt involved hot water, Simple Green and a scrub brush. The Simple Green removed a good portion of the grime, but things were still looking grim. Next in the arsenal came a spray can of a carb cleaner. Carb cleaner helped in a few spots, but still not great. I should have tried paint thinner, one of my new favorite part cleaning fluids...... next time. Lots of Googling suggested that aluminum wheel cleaner (the kind for wheels without a clear coating) was the thing to use. Well, it did a great job getting the rest of the gunk off, and with the gunk, the original shine/polish. I assume this was an acidic cleaner that etched the surface? Now, had a nice clean manifold that looked terrible. Had this been a relatively smooth casting, loosing the original polish would not have been a big deal because it would be trivial renew with metal polish. The rough "sand cast" surface creates problems for the metal polish. To avoid all these pitfalls, it seems as if most people decide to media blast and then followup  with a clear or metallic powder coat or paint. Other options seem to be grind off all the casting marks and surface irregularities to create a smooth surface that can be easily polished. The manifold is rough cast and it seems that most of the advice on the "interwebs" is geared toward manifolds that are inherently smoother. I had a hard time finding useful information on how to approach such a rough surface.

 I'm still weary of painting things and try to avoid it if possible.  I see paint as something that can scratch, peel, chip, discolor and always need to be repainted, therefore "natural" surfaces would seem the most durable and easy to maintain. Clearly, lots of people with MUCH more experience than I have in these matters paint these things, they must be on to something. The paint looks good and may even aid in cleaning by creating a smoother surface that oil and grease can be wiped off.

I decided I would try to polish my now clean and dull manifold although after the cleaning described above, maybe I should have just painted it. Live and learn.  Just taking polish to the surface only shined the high parts, simultaneously filling the voids with black residue, not so good. A carbon steel wire brush on a Dremel seemed to do a good job, but I was worried that I might be causing the aluminum  on high parts to actually smear over the pores, possibly entrapping stuff in the pores of rough cast surface.  As I used the wheel I noticed the apparent porosity of the surface diminishing, without the apparent removal of material. The dremel did help clean up hard to reach areas, but mostly I went after/over the whole thing first with a rough and then a smooth Scotch Bright pad, followed by metal polish and a few rounds of scrubbing out the reside with a toothbrush and dish soap. Actually, the dish soap was not so good at removing the residue from the Mothers polish; Mr. Clean worked better.

Here is the finished version, before replacing all the fittings.

The manifold certainly looks much better than when when the process started. If I were starting again, I would try using Never Dull wadding polish after the Simple Green. The Never Dull did not produce a great shine (Mothers did that),  the solvents it contained were effective at cleaning the surface and it certainly would not have damaged the surface like the wheel cleaner. I wonder if Mothers polish contains more fine abrasives than the Never Dull.  The final result is not perfect, but certainly a step in the right direction. I can always work on it latter, right now there are bigger fish to fry, like all the other parts and the seized engine....